A campaigner against the death sentence, Mitchell wrote to Florida governor Jen Bush on Hill’s behalf. In his letter, Mitchell pleaded that Hill had committed a senseless crime but that ‘executing him would only perpetuate the cycle of taking life’.

Governor Bush ignored Mitchell’s plea and Hill, who claimed he was a martyr for the anti-abortion cause, was put to death by injection.

A spokesperson for Mitchell has denied to the Irish Examiner that the 2003 letter bears any comparison to Senator Norris’ appeal for clemency for a convicted child rapist.

“Mr Mitchell did it because he is an implacable opponent of the death penalty,” said the spokesperson.

“It is different to the Norris situation in that he was seeking that the death penalty be replaced by a term in prison. He wasn’t seeking mitigation.

“Mr Mitchell has also intervened on behalf of other prisoners facing the death penalty.”